docs: def rmswidth(self, floor=0):
          """Calculate :ref:`pysynphot-formula-rmswidth`.
  
          Parameters
          ----------
          floor : float
              Throughput values equal or below this threshold are not
              included in the calculation. By default (0), all points
              are included.
  
          Returns
          -------
          ans : float
              RMS band width.
  
          """
          mywaveunits = self.waveunits.name
          self.convert('angstroms')
  
          wave = self.wave
          thru = self.throughput
          self.convert(mywaveunits)
  
          if floor != 0:
              idx = N.where(thru >= floor)
              wave = wave[idx]
              thru = thru[idx]
  
          integrand = (wave-self.avgwave())**2 * thru
          num = self.trapezoidIntegration(wave, integrand)
          den = self.trapezoidIntegration(wave, thru)
  
          if 0.0 in (num, den):
              return 0.0
          else:
              ans = math.sqrt(num/den)
              return ans